Non-Sampling
Error
Sampling Error
Selection Bias
Non-Response Bias
Question Effects
Transfer of Findings
Survey-Format Effects
Self-Selection Bias
Interviewer Effects
Behavioural
Considerations
“The Centre for the Study of Higher Education
A news article reads:
has sought Macquarie’s support to survey a
“A new breed of campers is using
representative sample of their academic staff.
smartphone apps to make the most of their
Interested members of staff should contact
holidays”
Professor John Loxton about obtaining copies of
The survey involved 400 people aged
the survey questionnaire."
18 and over
A website devoted to preventing
harassment of women reported that their
poll confirms that nearly all women were
victims of harassment at some point in
their lives.
Sampling Frame Error
A news article headline reads:
“Kiwis Agree – Make Uniforms for School
Students Compulsory”
This survey involved 400 Aucklanders aged
18 and over
18 August 1980 New York Times/CBS News Poll
In 1968, one year after a major racial disturbance in
“Do you think there should be an amendment to the
Detroit, a sample of black residents were asked:
constitution prohibiting abortions?”
Yes
29%
No
62%
Later the same people were asked:
“Do you think there should be an amendment to the
constitution protecting the life of the unborn child?”
Yes
50%
No
39%
“Do you personally feel that you trust most white
people, some white people or none at all?”
•
White interviewer:
35% answered “most”
•
Black interviewer:
7% answered “most”
The New Zealand Herald randomly selected
Nurses at Plunket were asking mothers to
one hundred 20 year-olds from the electoral
complete a survey on their drinking and
roll in Auckland and asked them who the voted
smoking habits.
for in the last election.
Auckland opinions used to represent
New Zealand opinions.
A survey was conducted over the telephone. As
a result people without a telephone were excluded
from the survey.
Ratings for television programs are estimated from
approximately 2000 randomly contacted viewers.
A breakfast cereal company visits the local
This sample was used to represent the television
supermarket to survey children about the price
preferences of a total population of 12 million
of breakfast cereal.
Canadian households. 15% of those contacted
agreed to partake in the survey.
In the 1936 presidential election (in the USA)
Online Polls: These polls are completed only by
between Roosevelt & Landon a sample frame was
visitors to the site, and so those with an interest in
obtained from car registrations and telephone
directories. In 1936, many Americans did not own
cars or telephones and those who did were largely
Republicans. The results wrongly predicted a
Republican victory.
The NZ Health Questionnaire includes 500
multiple choice questions for each respondent to
answer.
the website take part in the polls.